Answers

Here are three I found off the top of my head. Disaboom is pretty slow but usually good at keeping out devotees and weirdos. There are lots of facebook groups but like with the links I mentioned watch out.
If you're looking for online support groups the best thing you can do is contact organizations like The Amputee Coalition of America , The War Amps or your local prosthetic clinic. They should be able to help you find links to safe or mostly safe amputee websites.